To describe 1-year mortality among preterm infants with hemodynamically significant CHD, identify associated risk factors, and develop a score to predict mortality at 1 year.

Retrospective multicenter cohort study conducted in 5 French tertiary M3 C centers (Montpellier, Bordeaux, Marseille, Nantes, Toulouse). All infants born at < 37 weeks’ gestation with hemodynamically significant CHD managed between 2018 and 2023 were eligible. Minor lesions without expected hemodynamic impact were excluded. Severe neonatal morbidity was also assessed (IVH grade III/IV, NEC Bell stage ≥ 2a, severe BPD, BPH).

Among 213 preterm infants with significant CHD (median gestational age, 34 weeks; mean birth weight, 1959 g), 1-year mortality was 21.1%. The most frequent CHD categories were complex right ventricular outflow tract anomalies (40.9%) and extracardiac arterial trunk anomalies (14.6%). One-year survival without severe neonatal morbidity occurred in 69.0%. In multivariable survival analysis, one-year mortality remained associated with lower gestational age (aHR 0.88, 95% CI 0.79–0.98; P = 0.02), lower 10-minute Apgar score (aHR 0.76, 95% CI 0.68–0.86; P < 0.001), genetic/syndromic anomalies (aHR 3.55, 95% CI 1.73–7.30; P = 0.0006), mixing CHD physiology (aHR 4.64, 95% CI 2.32–9.30; P < 0.001), high-grade intraventricular hemorrhage (aHR 8.99, 95% CI 2.92–27.68; P = 0.0001), and prostaglandin infusion (aHR 1.92, 95% CI 0.97–3.78; P = 0.0596). A prediction score for 1-year mortality was derived from the final multivariable model.

In this contemporary cohort of preterm infants with hemodynamically significant CHD, mortality through 1 year remained substantial. Risk was associated with early postnatal adaptation, CHD physiology/comorbidity, and early markers of illness severity. An early risk score provided pragmatic risk stratification, but larger contemporary cohorts are needed to better characterize morbidity patterns and improve model performance and generalizability.